Surface texture for fibrous boards

ABSTRACT

An aesthetically pleasing texture is imparted to wet-laid fibrous mats by distributing a layer of solid expanded particles of synthetic thermoplastic resinous foamed material on the upper surface of the mat. The particles are then pressed into the wet lap to embed the particles in the fibrous material and the wet lap is subsequently heated to reduce the volume of the particles and leave depressions in the surface which result in a unique random surface texture.

Umted States Patent 1 1 1111 3,870,540 Norgard Mar. 11, 1975 [541 SURFACE TEXTURE FOR FIBROUS 2,302,020 11/1942 Frederick 162/115 BOARDS 2,760,881 8/1956 Toulmin 117/9 2,819,178 1/1958 Haracz 117/9 Inventor: Fred g 45 Mane 2,862,834 12/1958 H1161 117/41 Somervi11e,N.J. 08876 2,936,814 5/1960 Yakubik 117/9 2,996,389 8/1961 Fernhof 264/D1G. 7 1221 Flledi 5, 1972 3,176,054 3/1965 Einstein et al. 264/D1G. 7 [211 App]. No.1 241,161 3,634,562 1/1972 K016 et a1. 264/41 Related Applicafin" Data Primary Examiner-George F. Lesmes [63] Continuation-impart of Ser. No. 49,325, June 24, A i tant Ex miner-Pau1 ,1. Thibodeau 1970 abandoned Attorney, Agent, or Firm-Robert M. Krone; James W.

McClain [52] US. Cl 117/16, 117/28, 117/65.2, 161/116,161/162,161/168,161/413,

162/152, 156/279 [57] I APSTRACT [51] Int. Cl B32b 19/00 An aesthet'cany Pleasmg texture mpaned to [58] Field of Search 161/139, 159, 413, 162, laid fibrous ar y i tributing a layer of SOIid ex- 161/116, 168; 264/41, 44 DIG. 16 7, 17; panded particles of synthetic thermoplastic resinous 7/9, 41, 25, 16, 65.2. 156/77, 2,79, 84; foamed material on the upper surface of the mat, The {62/115, 207 152 particles are then pressed into the wet lap to embed the particles in the fibrous material and the wet lap is 56] References Cited subsequently heated to reduce the volume of the parti- UNITED STATES PATENTS cles and leave depressions in the surface which result in a uni ue random surface texture. 1,513,620 10/1924 Maclldowie 161/413 q 1,945,004 1/1934 McQuade 117/9 5 Claims, 4 Drawing Figures 1 SURFACE TEXTURE FOR FIBROUS BOARDS This application is a continuation-in-part of application Ser. No. 49,325, filed on June 24, 1970, now abandoned.

FIELD OF THE INVENTION This invention relates to ornamental compostion boards suitable for use as tiles and panels in ceilings and other walls of buildings, and to a method for making such boards. The invention is particularly applicable to fibrous composition boards made by processes involving the formation of a wetlap, as by wet-felting of water-laying of a fibrous mix from an aqueous slurry on a Fourdrineir or cylinder machine or by other techniques for forming fibrous wet laps which may be dried to produce the composition boards. While the invention has utility with various types of fibrous composition boards, including wood and other cellulosic fiber boards well-known in the industry, it is exceptionally effective and will be chiefly described and illustrated in its application to mineral fiber boards and particularly mineral wool boards.

BACKGROUND OF THE INVENTION Fibrous composition boards have been used for years in interior ceilings and other interior walls of buildings to provide exposed surfaces which are ornamental or decorative and which preferably also function to improve the acousticaal properties of the walls. It has been a popular practice to form perforations, fissures, cavities, and other forms of openings of various types and shapes, on the surface of the board to be exposed to impart improved aesthetic and acoustical properties to the boards.

These openings typically have been formed by mechanically drilling, punching, piercing or die-forming the dry board stock produced by drying the wet lap. In some cases the surface of the dried board has been brushed or abraded or eroded by sandblasting to impart a roughened texture to portions of the visible surface in attempts to provide additional or different aesthetic effects. Before drying, however, the wet lap has very little strength. While some types of surface texturing and fissuring have been performed on the wet'lap before drying it, as by dragging the surface of mineral fiber wet lap board stock with a screed or drag bar to form fissures in it, the type and amount of working of the surface prior to drying of the wet lap are limited by the lack of strength of the wet lap and by other properties and characteristics of the wet lap.

The walls or boundaries of the fissures or textural contours are usually more cleanly defined if they are produced in the surface of the board after it has been dried, rather than before, and because this clean definition has been favorably regarded, much emphasis has been placed on the techniques of treating the surface of the dry board. This procedure has some disadvantages, however, such as a tendency to weaken the 3 board by severing or tearing the fiber network after the board has been dried or set. Thus, in spite of the keen composition and incentive in the trade to produce boards with new and superior aestheticeffects and with at least adequate acoustical and other properties, success has been limited. Only a relatively few basic practical techniques for surface treatment, to open or contour the surface of the boards, have been found feasible OBJECTS OF THE INVENTION A primary object of the present invention is to provide a composition board of the general type discussed above but having a fresh and strikingly different and pleasing visual apeal.

A further object is to provide such a board having adequate or improved acoustical characteristics.

A further object is to provide such a board having adequate or improved properties of strength, fireresistance, sag-resistance, and other utilitarian features.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description. or may' be learned by practice of the invention.

SUMMARY OF THE INVENTION The objects and advantages of the invention are achieved by producing unique and pleasing aesthetic effects on fibrous boards by distributing a layer of particles ofa synthetic thermoplastic resinous foamed material on one surface of a water-laid lap of entangled fibers before pressing the lap, and then pressing the particles into the wet lap to embed the particles in the wet lap. Subsequently, the wet lap having the particles embedded in one surface is heated to reduce the effective volume of the particles and leave depressions in the surface which produce a unique surface texture.

The invention includes a fibrous board which has a decorative surface texture on one face comprising a water-laid compressed mat of entanged fibers containing surface craters. A portion of the surface area of the craters is coated with thermoplastic material. Fibrous areas are positioned between a substantial number of the craters, with the fibrous areas possessing a substantially rougher exterior surface than the walls of the erater which are formed by fibers that undergo intense compressive stress during the pressing operation.

DESCRIPTION OF THE DRAWINGS FIG. 3 is an enlarged sectional elevation view of a portion of the board of FIG. 2 taken along line 33 of FIG. 2; and,

FIG. 4 is an enlarged sectional elevation view of a portion of another board having the unique surface texture of this invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In accordance with the method of the invention, solid synthetic organic thermoplastic resinous foamed particles are deposited on the surface of a water-laid mat of entangled fibers, and are then embedded in the mat of fibers. Subsequently, the fibrous mat is heated to decrease the volume of the foamed particles and create depressions in the surface of the mat.

The solid foam particles which are deposited on the surface of the mat can be selected from a large variety of solid thermoplastic synthetic resinous foamed materials which contract in volume upon exposure to moderate heat. In preferred embodiments of the invention, the material in the finished board has less than 50 percent of its initial volume. Suitable solid particles include expanded or foamed particles of thermoplastic synthetic resinous material which, when melted, occupy a substantially reduced volume compared to their expanded condition. Preferably, the solid foam particles vary in size and have a largest dimension between about /a and /1 inches. However, the particles can be uniformly sized, or can be larger or smaller than the preferred size range.

The solid particles can comprise beads of any synthetic organic resinous thermoplastic material which can be expanded or foamed. Typical examples include polystryrcne, polyethylene, polypropylene, poly(vinyl chloride), poly (methyl methacrylate).and nylon, as well as copolymers and blends therof. Preferred are polystryene, polypropylene, poly(vinyl chloride), and polyethylene, with polystyrene being most preferred because of its low cost, readily availability, and ease of handling. When these materials are heated, the thermoplastic material stays on the surface of the board but is greatly reduced in volume. It has been found that ost synthetic organic thermoplastic resinous foam materials, when melted, tend to formsmall spherical particles at the bottom of the craters.

The solid particles can be distributed on the surface of the wet lap in any convenient manner. Preferably, a feeding apparatus is used that deposits a precise, predetermined quantity of solid particles across the cross section ofwet lap. The use of an agitated solids feeding mechanism in which the flow of solids is regulated by a valve or gate structure forms a suitable distribution procedure.

To avoid excessive disruption, it is frequently desirable to form a layer of beads that is one bead thick on the surface of the wet lap. Also, for aesthetic reasons it is desirable to have a majority of the beads in the onebead-thick (single) layer abut another bead or beads.

The solid particles are deposited on the surface of the wet lap before wet pressing and preferably before the solids content of the board reaches about 50 percent. A compressive force is applied across the thickness of the wet lap to embed the beads in the wet lap. The wet pressing step can be performed by a roll press such as used in pressing wet laps in Fourdrinier and cylinder machines.

Immediately after the pressing step, the surface of the wet lap which is to be textured tends to be substantially planar since the pressing operation embeds the solid particles into the fibrous mat.

After the solid foam particles have been embedded in the pressed wet lap, the wet lap is exposed to heat to reduce the volume of the foamed material and create void spaces in the surface of the board. In the heating step, the solid foam particles are heated at a temperature sufficient to cause them to decrease in volume. The particular temperature required will depend on the foamed material used, for the thermoplastic material must be raised to its melting point to achieve the reduction in volume.

The process of the invention does not disintegrate the wet lap or destroy its basic edge contours or dimensions, but it does strikingly alter the surface configuration of the wet lap. When rounded solid particles are distributed entirely across the surfaace of the board, a cratered appearance is provided that somewhaat resembles the surface of the moon.

Typical surface textures provided by this invention ,are illustrated in FIGS. 2, 3, and 4..A mineral wool board, generally 10, is formed by a mat of entangled fibers. A plurality of randomly arranged craters 12 are distributed across the upper surface of board 10, with narrow bands of fibrous areas 14 positioned between a substantial number of craters. The fibrous areas possess a rougher exterior surface than the walls of craters 12, which heightens the dramatic visual effect of the textured surface. It is believed that this variation in surface texture and appearance between the crater walls and the narrow bands results from the differeing amounts of compression which are applied across the face of the wet lap because of the presence of the thermoplastic beads on the surface during the wet pressing operation. The fibers forming the walls of the craters are subjected to more compression than the fibers positioned between the particles during the wet pressing operation.

In the embodiment of FIGS. 2 and 3, the surface of board 10 is coated with a paint layer 16, best illustrated in FIG. 3. A small volume of thermoplastic material is positioned in each crater as a result of melting the thermoplastic foamed beads. As illustrated in FIG. 3, the melted thermoplastic material comprises small globules 18 that are located at the bottom of the craters.

Over percent of the surface area of the board comprises craters in the embodiment illustrated in FIGS. 2 and 3. The craters when viewed from above the surface of the board,v are generally circular.

Paint layer 16, as illustrated in FIG. 3, covers globules 18 and masks the appearance of the globules. Paint layer 16 also tends to act as a binder and helps prevent globules 18 from being dislodged from board 10. It has been observed that even when sufficient paint is sprayed on board 10 to mask the appearance of globules 18, narrow bands 14 between the craters 12 retain a rougher surface texture and appearance than the wallls of the crater.

The board of FIG. 4 has not been painted. Globules 18 are visually apparent when looking down at the bottom surface of the craters 12 of ths board.

A specific example of the process of this inveniton will now be described with reference to FIG. 1. A mineral wool wet lap 20 is water laid from a fibrous aqueous slurry on the bottom screen 22 of a Fourdrinier machine. The board is formed from a 3.5 percent solids slurry containing 70.25 percent mineral wool, l5.25 percent clay, 9 percent starch and 5 percent defibered No. 1 newsprint in percent by weight of solids in the slurry.

Before the wet lap is pressed, and while the solids content of the wet lap is about 25 percent by weight,

foamed polystyrene beads 24 are deposited on the top surface of the wet lap from a dispensing hopper 26.

The expanded polystryene beads have a density of about 2 pounds per cubic foot, and vary in size from /8 to inch in diameter. The beads are distributed uniformly across the width of the moving wet lap to form a layer of abutting beads that is only one bead thick.

The foamed beads 24 are pressed into the top surface of the wet lap by a top screen 28 of the Fourdrinier press, which embeds the beads in the wet lap. The nip pressure exerted on the board is within the standard 200 300 psi range commonly employed during wet pressing operations.

Subsequently, the wet lap having foamed beads 24 embedded on its top surface is passed through a drying oven 30 held at about 350F which melts foamed beads 24 to cause a decrease in the volume of the beads and the formation of craters in the upper surface of the fibrous lap. Over 75 percent of the area of the surface comprises craters.

The dried board is sprayed with a white acrylic melamine primer and then an acrylic latex paint to form a board having a surface texture similar to that illustrated in FIGS. 2 and 3.

What I claim is:

l. A method of texturing the surface of a water-laid lap of entangled fibers comprising:

a. forming a water-laid lap of entangled fibers;

b. substantially uniformly distributing a layer of discrete particles of a foamed synthetic organic thermoplastic resinous materials on one surface of the water-laid lap of entangled fibers such that most of the particles abut one another before pressing the wet lap;

c. pressing the particles into the wet lap to embed the particles in the wet lap; and,

d. heating the wet lap to reduce the volume of the foamed material and leave depressions in the surface which produce a unique random surface texture.

2. The method of claim 1 wherein the thermoplastic material is selected from the group consisting of polystyrene, polyethylene, polypropylene, poly(vinyl chloride), poly(methyl methacrylate), nylon, and copolymers and blends thereof.

3. The method of claim 2 in which the thermoplastic material is polystyrene.

4. The method of claim 2 including the step of paint ing the surface of the resulting board after the heating step to alter the visual appearance of the board and to help bind the thermoplastic material to the surface of the board.

5. The method of claim 2 in which the particles of foamed thermoplastic material vary in size and have a largest dimension between about Va and inches.

' l =l l= UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 870, 540 DATED March 11, 1975 INVENTORL'S) 1 Fred c, Norgard i t'is certified that error appears in the shew-identified patent and that said Letters Patent are hemby corrects as shown below:

Column 1, line 14, "of" should read "or" Column 1, line 15, "Fourdrinier" had been misspelled Column 1, line 30, "accoustical" has been misspelled Column 1, line 62, "composition" should read "competition" Column 2, line 9, "practice" should read "practicable" Column 2, line 18, "appeal" has been misspelled Column 3, line 34, "readily" should read ready" Column 3, line 37, "0st" should read "most" Column 4, line 13, "surface" has been misspelled Column 4, line 27, "differing" has been misspelled i Column 4, line 53, "walls has been misspelled Column 4, line 56, "ths" should read "this" Column 4, line 58, "invention" has been misspelled ,Column 6, line 3, "materials" should read "material" Signed and Sealed this twenty-third D ay Of September 1975 [SEAL] A ttesr:

RUTH c. MASON c. MARSHALL DANN HH IX ffil ('lmlmissimu'r nflarcnrs and Trademarks 

1. A METHOD OF TEXTURING THE SURFACE OF A WATER-LAID LAP OF ENTANGLED FIBERS COMPRISING: A. FORMING A WATER-LAID LAP OF ENTANGLED FIBERS: B. SUBSTANTIALLY UNIFORMLY DISTRIBUTING A LAYER OF DISCRETE PARTICLES OF A FOAMED SYNTHETIC ORGANIC THERMOPLASTIC RESINOUS MATERIALS ON ONE SURFACE OF THE WATER-LAID LAP OF ENTANGLED FIBERS SUCH THAT MOST OF THE PARTICLES ABOUT ONE ABOTHER BEFORE PRESSING THE WET LAP, C. PRESSING THE PARTICLES INTO THE WET-LAP TO EMBED THE PARTICLES IN THE WET LAP, AND, D. HEATING THE WET LAP TO REDUCE THE VOLUME OF THE FOAMED MATERIAL AND LEAVE DEPRESSIONS IN THE SURFACE WHICH PRODUCE A UNIQUE RANDOM SURFACE TEXTURE.
 1. A method of texturing the surface of a water-laid lap of entangled fibers comprising: a. forming a water-laid lap of entangled fibers; b. substantially unifOrmly distributing a layer of discrete particles of a foamed synthetic organic thermoplastic resinous materials on one surface of the water-laid lap of entangled fibers such that most of the particles abut one another before pressing the wet lap; c. pressing the particles into the wet lap to embed the particles in the wet lap; and, d. heating the wet lap to reduce the volume of the foamed material and leave depressions in the surface which produce a unique random surface texture.
 2. The method of claim 1 wherein the thermoplastic material is selected from the group consisting of polystyrene, polyethylene, polypropylene, poly(vinyl chloride), poly(methyl methacrylate), nylon, and copolymers and blends thereof.
 3. The method of claim 2 in which the thermoplastic material is polystyrene.
 4. The method of claim 2 including the step of painting the surface of the resulting board after the heating step to alter the visual appearance of the board and to help bind the thermoplastic material to the surface of the board. 